Abstract

The orbitals of the ground state of a flat conjugated molecule are shown to be closely related to the orbitals of a certain excited state of the molecule. In this state, which is named the standard excited state, all the mobile electrons are in singly-occupied antisymmetrical or $\pi $ orbitals and have their spins parallel. These antisymmetrical orbitals can be transformed into equivalent orbitals which are each localized around one atom and so form a suitable basis for a method of calculating the ionization potentials of conjugated molecules. To illustrate the form of the equations obtained, the pyridine and aniline molecules are considered.